This invention relates to a thyratron switch for producing pulses having a very narrow width, and more particularly to generation of narrow pulses for modulation of millimeter wave tubes.
Narrow pulse modulation of millimeter wave tubes is required in order to achieve improved pattern recognition and resolution in radar systems. The required modulation characteristics are typically: pulsewidths less than four nanoseconds, pulse repetition rates greater than 20 kilohertz, jitter less than one nanosecond, and pulse amplitudes of 2 to 15 kilovolts (the particular voltage depends on the tube type). For the long term future, such modulators will most likely rely on solid state devices such as avalanche transistors, or possibly pulse sharpening devices. Since the ultimate risetime capability of the solid-state devices is in the subnanosecond range, millimeter wave systems with extremely good resolution are foreseen. Until such devices are developed, however, an interim solution for obtaining narrow pulse modulation appears feasible using conventional thyratrons. Thyratrons satisfy both the voltage and pulse repetition rate requirements, but the risetime capability is marginal. This naturally limits the ability of the thyratron to produce the necessary narrow pulse.